Better short-term clinical response to etanercept in Chinese than Caucasian patients with active ankylosing spondylitis

Tumor necrosis factor-alpha (TNF-α) inhibitors including etanercept have been demonstrated to be very effective in severe ankylosing spondylitis (AS) in Caucasian patients. However, clinical efficacy of etanercept to treat active AS in Chinese patients has not been reported. In this study, a prospective, open-label trial of etanercept (25 mg BIW), involving 46 AS patients from 16 medical centers of Taiwan, was conducted. Questionnaire was utilized to record demographic data and clinical parameters, including Bath AS Disease Activity Index (BASDAI), Bath AS Functional Index (BASFI), Bath AS Global Index (BASGI), Assessment in Ankylosing Spondylitis (ASAS) 20, 50, and 70, and others, before and at different time intervals after etanercept treatment. Laboratory tests including blood chemistry, hematology, urine analysis, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) were done at baseline and at weeks 4, 8, and 12. In this 12-week study, etanercept demonstrated rapid and significant improvement in the ASAS20 response criteria (91.3%), at as early as 2 weeks of therapy (71.3%). Partial remission of AS was achieved in 49.3% of patients after 12 weeks of treatment. Disease activity (BASDAI) and function (BASFI) were also significantly improved after 12 weeks etanercept treatment (p < 0.0001 and p < 0.0001, respectively). In addition, significant increase of chest expansion (2.77 ± 1.69 cm versus 3.56 ± 1.82 cm, p = 0.0004) and lumbar flexion (2.11 ± 2.76 cm versus 2.58 ± 3.42 cm, p = 0.0075) and significant reduction of occiput-to-wall distance (6.59 ± 7.14 cm versus 5.32 ± 6.65 cm, p = 0.0006) were also demonstrated. Both ESR and CRP declined significantly after patients were treated with etanercept. There were no severe adverse effects during the treatment period. Etanercept is generally safe, well tolerated, and effective in Chinese patients with severe AS. Clinical efficacy, including partial remission and BASDAI, is even better in Chinese than in Caucasian patients. Further study is required to assess long-term efficacy and safety in Chinese patients with AS.